The following description of the Background is intended provided to provide helpful information and is not considered by the Applicant to be admitted prior art. Some of the observations discussed may well be observations made contemporaneously with the conceptual developments of the inventive concepts and are not admitted to being known by those of average skill in the art.
Constant reference currents that remain substantially constant despite changes in device temperature and loading are needed. In many reference current generation circuits that include resistive elements and MOSFET transistors, reference currents fluctuate with temperature changes. Current often increases with temperature. Accordingly, current consumption increases for circuitry whose operations are based on the reference currents. Such increases in current consumption lead to increases in power consumption and, for portable electronics, a decrease in battery life. It is desirable, therefore, to develop reference current sources that operate substantially independent of temperature changes and loading conditions.
In addition, not only do temperature dependent current increases undesirably power consumption and decrease battery life, increases in reference currents can also degrade performance of analog circuits. This result occurs because the changed reference currents may change the bias conditions for analog circuitry and therefore their operating characteristics. While there are circuits that utilize trimming or calibration technology, such solutions are expensive in terms of IC real estate and associated power consumption. Accordingly, a need exists for stable reference current sources that fluctuate less due to temperature increases.
The use of the same reference symbols in different drawings indicates similar or identical items. Unless otherwise noted, the word “coupled” and its associated verb forms include both direct connection and indirect electrical connection by means known in the art, and unless otherwise noted any description of direct connection implies alternate embodiments using suitable forms of indirect electrical connection as well.